1. Field of the Invention
This invention relates to the preparation of .alpha.-alkyl and .alpha.-aryl substituted acrylic acids and esters and more particularly to those derived from fatty acids such as lauric, myristic, palmitic, stearic and oleic acid. The invention also relates to a process for making the substituted acrylic acids in high yield and high purity.
2. Description of the Prior Art
The preparation of .alpha.-substituted acrylic acids is known in the art. However, these known methods are not useful except for the preparation of laboratory scale quantities, because these methods require that the heat of reaction be controlled to avoid the production of numerous by-products. In one of the more recent methods, Pfeffer et al (U.S. Pat. No. 3,912,772 and J. Org. Chem. 37, 1256, 1972) modified Creger's synthesis (JACS 89, 2500, 1967) in tetrahydrofuran at low temperature by the use of hexamethylphosphoramide. It is known in the art, U.S. Pat. Nos. 2,734,074 and 3,247,248, that formaldehyde reacts with lower alkyl esters of aliphatic monocarboxylic acids having at least two hydrogen atoms attached to the .alpha.-carbon atom to produce lower alkyl esters of .alpha.-.beta.-unsaturated acids. The procedures work only for the lower molecular weight .alpha.-substituted acrylic acids and do not work for the non-vaporizable higher molecular weight fatty acids of the subject invention. Gisser et al (U.S. Pat. No. 3,687,922) disclose the production of dodecylmalonic half acid-half ester which is reacted with diethylamine and formaldehyde to obtain methyl-.alpha.-n-dodecylacrylate. However, the yield is only 37% and the procedure requires the use of moisture sensitive and expensive reagents which are not needed in the instant invention.